Multiple switch-board



(No Model.)

M. G.KELLOGG.

MULTIPLE SWITCH BOARD. N6. 385,863. v Patented July 10, 1888 m Mead 6%.

MILO G. KELLOGG, OF HYDE PARK, ILLINOIS.

MULTIPLE SNlTCH-BOARD.

EPECIPICATION forming art of Letters Patent No. 385,863, dated July 10,1888.

(X0 model.)

To aZZ whom it may concern:

Be it known that I, MILO G. KELLOGG, of Hyde Park, Illinois, haveinvented certain new and useful Improvements in Multiple Switch-Boardsfor Telephone-Exchanges, of which the following is a full, clear,concise, and eXact description, reference being had to the accompanyingdrawings, forming a part of this specification.

My invention relates especially to a telephone-exchange system in whichthe subscribers lines are grounded at the central office.

It consists, first, of a multiple switchboard system of operating anexchange and testing at any board to determine whether any given line isin use, which system I shall hereinafter describe and claim in detail.

It consists, secondly, of an operators system of cords, apparatus, andcircuits for answering, calling, switching, and clearing out subscriberslines, which system I shall hereinafter describe and claim in detail,said system being applicable to said multiple switchboard systemmentioned above and to other systems of telephone-exchangeswitch-boards.

In my multiple switch-beard system I place as many switch-boards in thecentral office as are found necessary, in order to answer the calls andconnect and disconnect the subscribers lines. On each board I place foreach telephone-line which centers at the office a springjacl; or similarswitch having three insulated contact-points, two of which are normallyin contact, said switch being adapted to receive a plug, and when theplug is inserted to disconnect the points which are normally in contactand connect one of them and the other contact-point to the metal pieceof the plug, to which is attached a flexible conducting-cord, and whenthe plug is withdrawn to again connect the contact-points which arenormally in contact and disconnect those which are in contact while theplug is inserted. The switches of a line on the different boards may becalled a series of switches. I place near each switch an insulatedcontact-piece, which I use as atest-bolt of itsline. These test piecesor bolts on the different boards belonging to a given line may be calledaseries of test pieces or bolts.

Figures 1 and l" of the drawings are front views ofsections oftwomultiple switch-boards to which the same wires are connected. Fig. 2shows a complete diagram of the boards with their connections and allthe central-office apparatus, circuits, and connections necessary tooperate them according to my invention.

In the drawings like parts and apparatus are indicated by the sameletters of reference.

In Fig 2, A is asectional viewof the switchboard shown in Fig. 1, asindicated by line (1 e,- and A is a sectional view of the switch-boardshown in Fig. 1", as indicated by line (1 c.

a b represent rubber strips on which the metal parts of the spring-jackswitches are mounted. These strips may be long enough to receive anyconvenient number of spring-jack parts.

Z Z, &c., are square holes through the fronts and at the edges of thestrips adapted to receive the switch-plugs.

The contact-springs g g, &c., are mounted to the rear of and areparallel to the holes I Z, &c., to which they belong, as shown. Thecontact-points h h, &c., on which the contactsprings or springleversnormally bear, pass through the strips, and have connecting-pieces h h,as shown. The contact-pieces jj of the switches are placed on one of thefaces of their respective switch-holes, as shown. The switch plugs aresubstantially as shown, and as will hereinafter be described.

The several parts mentioned above are so made, shaped, arranged, andadjusted that when a plug is inserted into any of the holes it raisesthe spring-lever in the rear of the hole from the contact-point on whichit normally bears, and the metal piece of the plug is connected to thespring-lever and also to the contact-piece Each section of a rubberstrip, with its springlcver, contact-point and contact-piece, and thehole, all arranged and operating as above, may be called a spring-jackswitch. The rubber strips are placed one above the other, as shown. Thelower edge of one strip therefore provides the upper edges of the holesin the strip which is below it. It is not necessary that the holesshould be actually square. They may be of any shape adapted to theshapes and arrangement of the parts used.

2' i are the test-bolts mentioned above. Each test-bolt is placed to theright of the springjack switch of the line to which it belongs.

It may, however, be placed in any other convenient place, providing itis so marked or placed that it may readily be known to what line itbelongs.

Twosubscribers lines are shown in the drawings. They are marked line No.1 and line No. 2. ss are theswitchesof lineNo. 1 on the two boardsshown, and r r are the switches of line No. 2 on the two boards shown.They may be single-circuit Wires grounded at the subscribers stations,and they pass through their series of switch-points g hon the differentboards, and to ground, passing first to the lever g of a switch, all inthe usual manner, and as shown. The other wires of the exchange would beconnected to their switches in like manner. Other boards might be addedto the exchange, and the circuit of the lines through their respectiveseries of switches on the different boards would be similar to theabove, and such as is usual.

w and at are calling-annuncjators. There may be one for each line, andthey may be distributed on the several boards, so that the operators mayconveniently answer the calls of the exchange. The annunciator w is forline No. 1 and a: is for line No. 2. Each annunciator is placed in thecircuit of its line after the line enters the office and before it goesto any pair of switch-points, g h, of any ofits series of switches. Fromeach line, after it enters the office and before it goes to itsannunciator, I branch a wire or wires to each of the contactpicces jj ofits series of switches. Wire s and its branches thus connect line No. 1with. contact-pieces j 7 of switches s and s, and wire 9" and itsbranches thus connect line No. 2 with contact-pieces jj of switches rand 1'. From each 1ine,after it enters the office and before it isconnected to any of the contact-springs g of its switches, and prefer-Only one pair of cords, with its plugs, key,

switch, and clearing-out annunciator,is shown in each system. Otherscould be added in a manner which will be apparent to those skilled pointit of the switch and form connection withthe lever g and contact-piecej.

G G are the rubber handles of the-plugs.

n n are connecting-pieces, as shown. 1 o is a metal piece connected tothe ground,

and on which the plugs normally rest, as shown, and by which the cordsare normally connected to the ground. Weights, in the usual manner, orother similar devices may be used to bring the pieces n on piece 0 andestablish agood connection.

Y is a looping-in switch.

3 y and z z are contact-bolts of the switch, on which the operator mayat will place the pair ofswitch-levers.

la is a calling-key, constructed, connected, and operating as shown. Aswitch or similar device might be used in its place.

1; is a clearing-out annunciator.

B is the operators signalinggenerator, and t is her telephone. She needsonly one generator and telephone for her cordsystem.

The circuits are substantially as shown.

T T are operators test systems. One system is shown at each board, andis intended for one operator. Each system consists of a flexibleconductor with a plug or testing device at one end and grounded at theother end by means of a conducting-wire, and a signal hell or device andan-electric battery or generator in the circuit between the plug and theground. 1 r

F is the test plug or device, and is so constructed that the operatorcan readily bring it into contact with any contact-piece or testbolt 1'at her board.

B is the test-battery, and E is the electric bell. The battery and bellshould be so adjusted to each other that the bell will ring when thetest-circuit described above is closed through a circuit of smallresistance-as, for

instance, that from any test-bolt 1' through the connections of its lineon and between the different boards and to ground, but will not 'ringwhen the test circuit or system is closed through a considerably largerresistance-as, for instance, that of a subscribersline and hissignal-bell, telephone, and ground, or that of ajoint conductor, thebranches of which are two subscribers lines connected together andpassing through their telephones orsignal-bells and to ground.

The differentparts of an operators cord system and her test systemshould be placed inconvenient arrangement at the board which sheattends, so that she can conveniently operate the exchange system. Thecords should be long enough to reach any of the switchesat the boards.

It is evident that when one switch-plug of a pair is iuserted,asdescribed, into any springjack switch of a line the line is opened atthe contact-points 9 7L of the switch and is disconnected from theground, and the flexible cord tact-piecej and their connecting-wires.

also evident that when this connection is made the calling-annunciatorof the line is shunted or short-circuited by the connecting-wire ofsmall resistance which connects the contact-piece j of its switch wit-hthe line.

It is IIO also evident that when the other switclrplug of the pair isinserted, as described, into the springjack switch of another line thatline is also opened at the contact-points g h of its switch, and istherefore disconnected from the g'round,and the flexible cord attachedto the plug is connected to the line both through the spring-leverg andthe contact-piece of the switch and connecting-wires. It is also evidentthat the two wires thus disconnected from the ground are connectedtogether for conversation,and that their annuneiators are shunted orshorteireuited by wires of small resistance, and that the operatorstelephone or the clearingout annuneiator c is in the circuit of thewires thus connected as the levers of the switch Y are on the bolts 2 zor y g It will also be seen that all the testbolts i of a line areconnected to the line whether it is switched for conversation or not.The linc-annnnciators, being thus shunt-ed or short-circuited by wiresof small resistance when their lines are switched for conversation, willnot retard the telephone currents by their magnetic action and will notbe actuated by the clearing-out signals, the latter being indicated onlyby the clearing-out annunciator which is in the circuit.

It will be seen that if the key it is depressed the two plugs areseparated or disconnected from each other and the plug D is groundedthrough the callinggencrator or battery B. It will therefore send acallingcnrrent to the line in whose spring-jack switch the plug isplaced.

The operation of the test system is as follows: If an operator at anyboard wishes to find out whether any given line is in use at anotherboard, she places her test plug ordevice on the test-boltt' of thelineon her board, and if the line is not in use her test-bell respondsbecause there is a closed circuit from the ground through her test-belland battery to the test-bolt, and thence through the springjacks andconnecting-wires of the line to the oiiice ground. It the line, however,is in use, by having a switclrplug in one of its springjaek switches onanother board the bell will not respond, because the circuit tracedabove is opened. There will of course in the latter case be a completecircuit from the ground through the tcstbell and battery through thesubscribers line and apparatus to the ground at the outer end of theline, and if another line is connected to the line tested through thatline and its subscribers apparatus and to ground at its outer end. Asstated previously, the bell and battery should be adjusted to eachother, so that the bell will not respond when the battery is closedthrough it and the lineeircuits, but will respond when the battery isclosed through the circuit from a testbolt to the otlice ground, asdescribed above. In practice it will be found that about one cell ofbattery and a signal of proportionate resist ance will answer therequirements of the test ing apparatus.

The test-bolts t 2' of a line are connected to l l t it between thesubscribers station and the switches, andv preferably, as heretoforeindicated, from a point between the line-annunciator and theswitch-springs. The test system would not operate as described if thebolts were not connected to their line between the station and theswitches.

The connection between a line and its testbolts is preferably made, asindicated, with the line-annunciator between the point of connection andthe subscribers station and not with it between the point of connectionand the ot'lice ground, for the reason that in the latter case atestingbattery would be required strong enough to actuate thetesting-bell through the resistance of the line-amiunciator and greatercare would be required to adjust its strength, so that it would not alsooperate the bell through the line-cirmritol' the line tested. it is forthis reason that the arrangement of an nunciators and circuits hereindescribed is preferable with this system of testing to that shown andclaimed in my patent, No. 247,199, of September 20,1881. I do not,however, wish to limit myself to the particular arrangement ofannuneiators herein shown and described, as my testing system isintended to include any arrangement of apparatus and cir cuits whereinthe battery and test-bell are so adjusted to each other and to thecircuits that the bell will respond when the battery is closed throughit and the line spring-jacks and the ot'lice ground, and will notrespond when it is merely closed through the subscribefls line to theouter ground.

The subscribers lines shown and described in this specification areclosed-circuit lines grounded normally at the central oftice andgrounded at the subscribers stations and pro vided with the usualoutfits at the stations.

The testing system is applicable to any arrangements of circuits inwhich the lines are normally grounded at the central and are disconnected from theground there when switched for conversation.

\Vhere a line is being tested and an aminociator is in circuit with it,whether it be its calling-annunciator or a clearing-out annuneiator, the:un'runciator should be so constructed and adjusted that it will not beactuated by the tcstingbattery used. Annunciators such as are ordinarilyused in telephoneexchange systems when placed in the circuit would notbe actuated similar to that indicated above and strong enough to operatethe test.

I claim as my invention and desire to secure by Letters Patent 1. In atelephone-cxehange system, the combination ol'lines normally grounded atthe central ol'tice with switches at the central ofiice, one switch foreach line, annunciators, one annunciator in each line placed in thecentral ol'llce between the line-switch and the subseribers station,branch wires, one wire branching from each line between its annunciatorand its subscribers station to an insulated piece of its switch, a pairof switch ICC plugs with flexible cords, and a clearing-out annunciator,said clearing-out annunciator being in a circuit which connects thecontactpoints of the plugs and each of said plugs being adapted wheninserted into a switch to disconnect the line which belongs to theswitch from the ground and to connect its contactpoint to the line boththrough the calling-annunciator and through the insulated contactpieceof the switch and its branch wire,whereby, by the insertion of the plugsinto the switches of any two lines, the lines are dis connected from theground and are connected together for conversation, theircalling-annunciators being shunted or short-circuited by wires of smallresistance, and the clearing-out annunciator being in the circuit of thelines so connected.

2. Ina telephone-exchange system, two subscribers lines temporarilydisconnected from the ground at the central office and connectedtogether for conversation, with their callingannunciators shunted bywires of small resistance, in combination with a clearing-outannunciator in the circuit of said lines, sub stantially as and for thepurpose set forth.

3. In a telephoneexchange system, two or DJOIQSWihCll-bOflI'dS at whichthe same lines are connected,switches,one for each lineon each board,and branch wires, one wire branching from each line between itscalling-nnnunciator and its subscribersstation to an insulated piece ofits switch on each board, in combination with switch-plugs with flexiblecords at each board, each of said plugs being adapted when inserted intoa switch to connect its contact-point to the line both-through thecalling-an nunciator and through theinsulated contact-piece of theswitch and its branch wire, whereby when a plug is inserted into theswitch of any line at either board the line is connected to the flexiblecord and its callingannunciator is shunted or short-circuited by a wireof small resistance, substantially as and for the purpose set forth.

4. In a telephone-exchange system, a telephone-line grounded at thesubscribers station and normally grounded at the central office, and aswitching device at the central office in the circuit of said lineadapted to disconnect the line from the ground and connect it withanother line for conversation, in combination with a test-bolt connectedto said line between the subscribers station and the switching device,(whether the line is switched or not,) a local test wire or circuit,said wire or circuit being grounded at one of its ends and connected atits other end to a switch-testing device adapted at the will of theoperator to be broughtinto connection with said test-bolt, atest-receiving instrument and a battery, said instrument and saidbattery being connected in said test wire or circuit between its endwhich is grounded and its end which is connected to said switch-testingdevice, said battery being so small (or weak) that it will not operatesaid testreceiving instrument when, on the test being applied and theline being switched for conversation, there is a complete circuitthrough the test instrument and battery to the ground at the subscribersstations only, but said battery being so strong as to operate saidtest-receiving instrument when, on the test being applied and the linebeing not switched for conversation, there is a complete circuit throughthe test instrument and battery both to the subscribers ground and tothe oflice ground of the line, substantially as and for the purpose setforth. v

5. In a telephone exchange system, tele phone-lines grounded at thesubscribers" stations and normally grounded at the central office, andtwo or more switch-boards for said lines, each board having a switchingdevice for each line, each switching device being sation, in combinationwith test-bolts, one for each line on each board, each test-bolt beingconnected to its line between the subscribers station and the switchingdevices of the line, local test wires or circuits, one for each board,each wire or circuit being grounded at one of its ends and connected atits other end to a switch-testing device adapted at the will of theoperator to be brought into connection with any test-bolt at her'board,a test-receiving instrument and battery for each test wire or circuit,the test instrumentand battery being in said wire or circuit between itsend which is grounded and the end which is connected to itsswitch-testing device, and the instrument being at the board to whichthe test-wire belongs, said battery being so small (or weak) that itwill not operate said test-receiving instrument when, on the test beingapplied and the line being switched for conversation, there is acomplete circuit through the test-receiving instrument and battery tothe grounds at the subscribers stations only, but said battery being sostrong as to operate said test-receiving instrument when, on the testbeing applied and the line being not switched for conversation, there isa complete circuit through the test-receiving instrument and the batteryboth to thesubscribersground and the officeground of the line,substantially as and for the purpose set forth.

6. In a telephone exchangesystem, a telephone-line normally grounded atthe central office by a ground-wire of small resistance,and a switchingdevice in the circuit of said line adapted to disconnect the line fromsaid ground-wire and connect it with another line for conversation, incombination with a testbolt connected to said line between thesubscribers station and the switching device, a local test wire orcircuit, said wire or circuit being grounded at one of its ends andconnected at its other end to a switch-testing device adapted at thewill of the operator to be brought into connection with said test-bolt,a test-receiving instrument, and a battery, said instrument and saidbattery being connected adapted to disconnect its line from the groundand to connect it with another line for conver-,

IIO

in said test wire or circuit between its end which is grounded and itsend which is connected to said switch-testing device, said battery beingso strong as to operate said testreceiving instrument when closedthrough the switching device and said ground-wire of small resistance,but so small (or weak) as not to operate said instrument when closedthrough a larger resistance, substantially as and for the purpose setforth.

7. In a telephone-exchange system, a telephoneline normally grounded atthe central o'tfice by a groun d-wire of small resistance, two or moreswitch-boards for the exchange, each board having a switching device forsaid line, each switching device being adapted to disconnect the linefrom said ground-wire and connect it with another line for conversation,in combination with test-bolts, one for said line on each board, eachtest-bolt being connected to the line between the subscribers stationand the switching devices of the line, local test wires or circuits, onefor each board, each test wire or circuit being grounded at one of itsends and connected at its other end to a switelrtesting device adaptedat the will of the operator to be brought into connection with thetestbolt at her board, a test-receiving instrument and battery for eachtest wire or circuit, the test-receiving instrument and battery being inits test wire or circuit between its end which is grounded and its endwhich is connected to its switclrtesting device, and each instrumentbeing at the board to which its test wire or circuit belongs, saidbattery in each test wire or circuit being so strong as to operate itstestreceiving instrument when closed through said switching devices andsaid ground-wire of small resistance, but so weak (or small) as not tooperate said instrument when closed through alargcr resistance,substantially as and for the purpose set forth.

8. In a telephoneexchange system, a telephone-line normally grounded atthe central oltice, a switching device for said line adapted todisconnect the line from its oilice ground and connect it with anotherline for conversation, and a eallingannuneiator in the circuit of theline between the subseribers station and the switching device, incombination with a test-bolt connected to said line between saidcalling-annunciator and said switching device, said test-bolt beingadapted to be connected at the will of the operator with a test wire orcircuit grounded at its other end, in which wire or circuit is atest-receiving instrument and battery,substantially as and for thepurpose set forth.

9. In a telephoneexchange system, two or more switchboards at which thesame lines are connected, switches, one on each board for each line,calling-annunciators, one for each line and connected in the circuit ofits line between the subscribers stat-ion and the switches of the line,test-bolts, one for each line on each board, each test-bolt beingconnected to its line between the line-switches and thecallingannunciator, each test-bolt being adapted to be connected at thewill of an operator to a test wire or circuit at its board, in which isa tcst-receiving instrument and battery, and branch wires branching fromeach line between its subscrihers station and its calling-annuneiator toan insulated piece of its switch on each board, in combination withswitch-plugs with flexible cords at each board, each of said plugs beingadapted, when inserted into a switch, to connect its contactpoint to theline both through the calling and through the insulated contact-piece ofthe switch and its branch wire, all substantially as and for the purposeset forth.

10. In a telephone-exchange system, the combination of the subscriberslines, the switch-boards, the switches, the an nunciators.circuit-connections between the switches and the subscribers linesthrough the annunciators, and separate circuit-connections between thesubscribers lines and the switches around or shunting the annunciators,substantially as set forth.

11. In a telephone-exchange system, the combination of a multipleswitcltl'ioard, the subscribers lines, the switches, one for each linein each heard, their circuit-conneclions, the tcst'bolts, one for eachswitch, connected to the lines between the subscribers stations and theswitches, the test-circuits connected with the lines, but normally inopen circuit therewith, a battery and signaling device in thetest-circuit, and a test-plug adapted to close the test-circuit at thetestbolt of any line, substantially as set forth.

12. In a telephoneexchange system, the combination of a multipleswitch-board, the subscribers lines, the switches, one for each line ineach board, their circuit-connections, the test-bolts, one for eachswitch, the test-circuit closed through the main line when the line isconnected up, but closed through a loeal circuit when the line is free,said test-circuit including a signaling device and a battery ofsut'licient strength to operate the signal when a circuit is closedthrough the unopened switches, but too weak to operate the signalthrough a circuit including one or more subscribers lines.

MILO G. KELLOGG.

\Vitnesses:

hIlLTON HEAD, CALVIN Dc \VoLF.

